JPH02248704A - Hydraulic pressure valve with pressure compensation - Google Patents

Abstract

PURPOSE:To prevent a valve from being set to excessive load pressure by deciding the set pressures of the first and second pressure compensation valves according to the maximum pressure in pressure detected by each check valve and providing a means for prohibiting the pressure compensation function from the outside. CONSTITUTION:When PPC (pressure control) valve 51 is operated by an operating lever 53 and the pilot pressure oil is supplied to the second pressure receiving chamber 262 to move a spool 12 to the right, the discharge pressure of a pump 22 is supplied through ports 15, 13, the second pressure compensation valve 30 and ports 17, 19 to a boom cylinder 23. Simultaneously, the hydraulic pressure from the port 13 works of a check valve 32 to be compared with the load pressure applied from the other hydraulic pressure valve with pressure compensation to a port 39, and the second pressure compensation valve 30 is set by the higher pressure. The same operation is conducted for a check valve 31. In the case of a rotating motor and a boom-up work, a pressure compensation changeover switch 56 is changed to input a signal to a controller 55, and an auxiliary selector valve 52 is switched by a lever 53 to put a switch valve 41 in a communicating position, whereby the pressure compensation function is prohibited. Thus, the valve can be prevented from being set to any excessive load pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic valve with pressure compensation provided in a hydraulic circuit of a power shovel, etc.

[Conventional technology]

Since a power excavator is equipped with multiple hydraulic actuators such as a swing motor, a travel motor, a boom cylinder, an arm cylinder, and a packet cylinder, its hydraulic circuit includes multiple hydraulic valves that supply hydraulic pressure to each hydraulic actuator. It is equipped with

In this way, in a hydraulic circuit equipped with multiple hydraulic/pressure valves, when two or more hydraulic valves are operated simultaneously, hydraulic pressure is supplied to the hydraulic actuator with a low load pressure, and is supplied to the hydraulic actuator with a high load pressure. Hydraulic pressure is no longer supplied.

Therefore, a hydraulic valve with pressure compensation has been proposed as shown in Japanese Patent Application Laid-open No. 188604/1983.

That is, as shown in FIG. 6, a spool 2 is provided in the valve body 1 to communicate and block the inlet port 3.4 with the operating ports 5 and 6, and a bridge passage Φ is blocked from communicating with the operating port 5. A pressure compensating valve is provided at 7, and this pressure compensating valve is configured to be set by the highest operating pressure of the plurality of hydraulic valves, so that a uniform flow rate is provided to the operating ports 5 and 6 of the plurality of hydraulic pressure valves with pressure compensation. By doing so, even if the load pressures differ when a plurality of hydraulic actuators are operated simultaneously, a uniform flow rate can be supplied to each hydraulic actuator.

[Problem to be solved by the invention]

Since such a hydraulic pressure valve with pressure compensation is always set to a pressure corresponding to the maximum load pressure, even if the working image with the maximum load is relieved, the pressure compensating valves of other working images will block the relief and reduce the flow rate. It operates to ensure that.

In other words, the flow rate distribution during simultaneous operations is performed accurately. This is true in terms of flow distribution, but on the other hand, it may be undesirable in terms of work efficiency.

For example, if we consider the swing motor of a power shovel,
When the swing motor starts swinging the upper body of the power shovel and accelerates it to a predetermined speed, the load acting on the swing motor due to inertia force becomes extremely large, and the load pressure on the swing motor becomes excessive.

That is, when the swing motor accelerates the swing, excessive load pressure is generated due to inertia force.

This excessive load pressure is higher than the set pressure of the relief valve, and flows out from the relief valve to the tank side.

If the boom is operated at this time, the boom raising speed will be slowed down by the amount of relief.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic valve with pressure compensation that can solve the above-mentioned problems.

[Means and operations for solving the problem] A first pressure compensation valve for compensating the pressure of the first working port and a second pressure compensating valve for compensating the pressure of the second working port are provided, and the first and second pressure compensating valves are provided.
This is a hydraulic pressure valve with pressure compensation that is equipped with a means for inhibiting the pressure compensation function of the pressure compensation valve from the outside, and thereby prevents the pressure of the first operating port and the second operating port from being set to a pressure that corresponds to the load pressure. from,
When an excessive load pressure is applied, it can be prevented from being set to that load pressure.

〔Example〕

As shown in FIG. 1, a spool 12 is fitted into a valve hole 11 of a valve body 10, and an outlet port 13 is formed in the axial middle of the valve hole 11. 1 and 2nd pump ports 14.15, 1st and 2nd ports 16° 17, 1st and 2nd operating ports) 18.19, and 1φ second tank port 20.21, respectively, are formed.
The 111th second pump ports 14 and 15 are the hydraulic pump 22
It communicates with the discharge side of the TSL/second operating port 18.19.
are in communication with a hydraulic actuator, e.g., the first and substantially second chambers 231 and 232 of the boom cylinder 23, and the 1Q and 2nd tank ports 20 and 21 are in communication with the tank 24, respectively.

The spool 12 is held at a neutral position where each port is blocked by a spring 25, and when pilot pressure is supplied to the first pressure receiving chamber 26 or the second pressure receiving chamber 262, it moves from the neutral position to the left and right and closes the first and second pressure receiving chambers. This will be the 2nd position.

A first passage 27 that communicates between the outlet port 13 and the first port 16 is provided with a first pressure compensating valve 28, and a second passage 29 that communicates with the outlet port 13 and the second port 16 is provided.
A second pressure compensating valve 30 is provided.

The first pressure compensating valve 28 has a poppet valve 31 with a valve seat 27a.
The poppet valve 31 is pressed against the check valve 3.
2 to form a back pressure chamber 34, which communicates with the first port 16 through a small hole 35 and through a liquid hole 36 formed in the piston 33. Communication is cut off to the pressure receiving chamber 37, and the poppet 31 is connected to the back pressure chamber 3.
4 and pressure-receiving chamber 37 are pressed against the valve seat 27a by the hydraulic pressure in the pressure-receiving chamber 37, and furthermore, the pressure-receiving chamber 37 is connected to the pressure introduction port 3 through a small hole 38.
9, and the piston 3 is opened by a spring 40.
3 is pressed against the bottom surface 37a of the pressure receiving chamber 37.

The on-off valve 41 is a pilot-type on-off valve that is held at the shutoff position I by a spring force and switched to the communication position by pilot pressure.

As shown in FIG. 2, the discharge hydraulic pressure of the pilot pump 50 is supplied to the first pressure receiving chamber 261 and the second pressure receiving chamber 262 of the spool 12 by a PPC valve (pressure control valve) 51, and is opened and closed by an auxiliary switching valve 52. It is supplied to the pilot pressure receiving part 41a of the valve 41, and the PPC valve 51 is operated by the operating lever 53. The switching stroke of the operating lever 53 is detected by the sensor 54 and sent to the controller 55, and the controller 55 switches the auxiliary switching valve 52.
The auxiliary switching valve 52 is switched when a switching signal is input.

Note that the second pressure compensation valve 30 is the same as the first pressure compensation valve 28.

Next, the operation will be explained.

Operate the PPC valve 51 with the operating lever 53 to open the second pressure receiving chamber 2.
When pilot pressure oil is supplied to 62 and the spool 12 is moved toward the second position on the right as shown in FIG.
7 and the second operating port 19 communicate with each other, and the second operating port 18
communicates with the first tank port 20.

As a result, the discharge pressure liquid of the hydraulic pump 22 flows from the second pump port 15 → the output port 13 → the second passage 29 → the second pressure compensating valve 30 → the second port 17 → the second operating port 19, and flows through the boom bottom 23. 10232, and the hydraulic pressure in the 10231 flows out from the first working port 18 to the first tank port 20 to the tank 24.

Note that the pressure compensation changeover switch 56 does not output a changeover signal, the controller 55 does not change over the auxiliary changeover valve 52, and the on-off valve 41 is in the cutoff position.

At this time, the hydraulic pressure flowing out from the outlet port 13 acts on the front surface of the poppet valve 31, separating the poppet valve 31 from the valve seat 27a and flowing to the second port 17.
9, that is, the load pressure flows through the fine hole 35, the back pressure chamber 34, the liquid hole 36, and the pressure receiving chamber 37, and is led to the pressure introduction port 39.

On the other hand, since this pressure introduction port 39 is communicated with each other in a plurality of pressure compensated hydraulic valves, the pressure in the pressure receiving chamber 37 becomes the maximum pressure, that is, the pressure corresponding to the hydraulic actuator with the highest load pressure, and the poppet The force with which the valve 31 is pressed against the valve seat 27a is determined by the pressure, so the second
The set pressure of the pressure compensation valve 30 is the set pressure most suitable for the hydraulic actuator.

The pressure introduction port 39 communicates with the capacity control member 42 of the hydraulic pump 22, and controls the capacity of the hydraulic pump 22 so that its discharge pressure P is lower than the detected maximum pressure P by a predetermined pressure, for example, 20 cg/ c-, and the meter-ine pressure ΔP1, that is, the pressure difference between the second pump port 15 and the outlet port 13 due to the communication area of the second pump port 15 and the outlet port 13, is controlled to be constant, for example, 20 kg/c-. Ru.

In addition, since the meter-in pressure difference in multiple pressure-compensated hydraulic valves is the same, when multiple pressure-compensated hydraulic valves are operated simultaneously, the fluid discharged from the hydraulic pump 22 is distributed and supplied to each hydraulic actuator. and can operate simultaneously.

In the case of lifting the swing motor and boom, the pressure compensation changeover switch 56 is changed over, a signal is input to the controller 55, and the auxiliary changeover valve 52 is changed over with the operation stroke of the operation lever 53, and the second pressure compensation is performed as shown in FIG. The on-off valve 41 on the valve 30 side is set to the communication position (3).

As a result, the pressure receiving chamber 37 in the check valve 32 of the second pressure compensation valve 30 communicates with the tank through the on-off valve 41.
Pressure compensation function is lost.

Therefore, the pressure in the second operating port 19 does not become high during turning acceleration, and the pump pressure is revised to the boom operating pressure when the boom is raised. That is, the swing motor is accelerated by the operating pressure of the boom lift, and the pump energy is utilized without loss.

Further, a switching signal may be outputted from the controller 55 to the auxiliary switching valve 52 in accordance with the operating stroke of the operating lever 53. For example, as shown in FIG.
It is also possible to set the auxiliary switching valve 52 to the communicating position only at the start of the operation in step 3 to eliminate the pressure compensation function, and to set the auxiliary switching valve 52 to the blocking position and provide the pressure compensation function when the operation exceeds a certain stroke.

In this way, the swing motor can be smoothly accelerated and decelerated.

[Effect of the invention] Since the pressure compensation function of the first and second pressure compensation valves can be inhibited from the outside, it is possible to prevent the pressure from being set to an excessive load pressure when an excessive load pressure is applied. The liquid discharged from the pressure pump does not wastefully flow out into the tank, making it more efficient.

[Brief explanation of drawings]

1 to 5 show examples of the present invention, in which FIG. 1 is a cross-sectional view, FIG. ff12 is a schematic explanatory view, and FIG. FIG. 4 is an explanatory diagram of the operation, FIG. 5 is a chart showing the relationship between the stroke of the operating lever and prohibition of the pressure compensation function, and FIG. 6 is a sectional view of a conventional example. 10 valve body, 12 spool, 14.15 1st and 2nd pump ports, 1g, 1 (Hl
ml/second operating port, 28.30 are the first and second pressure compensation valves, and 32 is the check valve.

Claims (1)

[Claims] In the valve body 10, the first operating port 18 is connected to and disconnected from the first pump port 14 and the first tank port 20, respectively, and the second operating port 19 is connected to the second pump port 15.
A first pressure compensating valve 28 is provided with a spool 12 that communicates with and blocks the second tank port 21 and sets the pressure of the liquid flowing from the first pump port 14 to the first operating port 18, and the first operating port 18. a second pressure compensation valve 30 that sets the pressure of the liquid flowing from the second pump 15 to the second operating port 19; and a check valve that detects the pressure of the second operating port 19. 32, the set pressure of the pressure compensation valve is determined by the highest pressure among the pressures detected by each of the check valves 32, and the pressure compensation function of the first and second pressure compensation valves 28 and 30 is prohibited from the outside. A hydraulic valve with pressure compensation, characterized in that it is provided with means.